Threatening letters containing a suspicious powdery substance, which so far has been found to be harmless, have been sent to a growing number of state offices of U.S. lawmakers, a top congressional law enforcement official said on Thursday.
Senate Sergeant at Arms Terrance Gainer said in an update to staff that several more Senate state offices had received threatening mail containing the suspicious powder.
The update followed a notice on Wednesday saying a number of members of Congress, including House of Representatives Speaker John Boehner, had received the letters that threatened a biological attack and contained a suspicious powder that tests found was harmless.
"While none of the mail received and tested thus far has been found to be harmful, it is clear that the person sending these letters is organized and committed, and the potential to do harm remains very real," Gainer said.
In 2001, deadly anthrax-laced letters were sent to several news organizations and Senate offices. Five people were killed and 17 sickened from the letters that went out as the country was reeling from the Sept. 11 attacks.
Gainer told congressional staff to remain vigilant even though tests showed the substance contained in the letters received by offices had so far been shown to be harmless.
Gainer said some of the latest letters shared the same return address as those that showed up on Wednesday. Others had a different address but were posted in the same Pacific Northwest region.
On Wednesday, officials said a number of media organizations and TV shows, including The New York Times and "The Daily Show with Jon Stewart," had also received mail, which was postmarked from Oregon. The sender warned that letters had been sent to the Washington or local offices of all 100 U.S. senators and that 10 contained a deadly pathogen, a law enforcement source said.
Gainer said Capitol law enforcement officials were working closely with federal and local law enforcement in an investigation into the mail.
(Reporting By Donna Smith; Editing by Peter Cooney)
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